This invention relates to organosilicon compounds and compositions thereof, wherein at least one alkoxy group has been transesterified with a diol. Compositions including transesterified organosilicon compounds exhibit improved hydrolytic stability and are suitable for imparting water repellency to various surfaces.
The use of organosilicon compounds as water repellants is well known in the art. The organosilicon compounds known and practiced in the art include ethoxy and methoxy functional groups attached to the silicon moiety. These compounds are typically supplied as a 100% concentrate or diluted in an appropriate solvent. Prior organosilane compositions are sensitive to hydrolysis in presence of moisture, which undesirably leads to the generation of ethanol or methanol during storage, transportation and use. Accordingly, the generation of methanol or ethanol undesirably lowers the flash point of these products and inherently increases the hazards of using these products.
Many organosilicon compositions are simply diluted in water and applied to various inorganic surfaces. It is often observed that during the hydrolysis of the silane-alkoxy groups, the resulting silanol groups produced in-situ participate in intermolecular or intramolecular condensation with the substrate. See E. P. Plueddemann, Adhesion Through Silane Coupling Agent., J. Adhe. 2, 184 (1970), E. P. Plueddemann, Silane Coupling Agents for high temperature resins, Soc, Plast. Ind. RPC Proc. 22, 9A (1967). E. P. Plueddemann, Cationic Organofunctional Silane coupling agents, Soc, Plast. Ind. RPC Proc. 27, 21B (1972). However, such intermolecular condensation needs to be avoided in order to achieve optimum performance. See Barry Arkles, Chemtech, Vol. 7 (1977). Therefore, it would be desirable to have oganosilicon compositions that are non-flammable, hydrolytically stable and exhibit reduced intermolecular condensation while also being suitable for imparting water repellency and surface modification.